drm/amd/powerplay: add global PowerPlay mutex.

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/inc/pp_instance.h

@@ -39,6 +39,7 @@ struct pp_instance {
 	struct pp_smumgr *smu_mgr;
 	struct pp_hwmgr *hwmgr;
 	struct pp_eventmgr *eventmgr;
+	struct mutex pp_lock;
 };
 
 #endif